diff -up OpenCPN-4.4.0/CMakeLists.txt.orig OpenCPN-4.4.0/CMakeLists.txt
--- OpenCPN-4.4.0/CMakeLists.txt.orig	2016-10-22 03:24:56.824710722 -0500
+++ OpenCPN-4.4.0/CMakeLists.txt	2016-10-22 03:28:10.592724737 -0500
@@ -101,6 +101,9 @@ IF (NOT WIN32)
   IF (EXISTS /etc/gentoo-release)
     SET (LIB_INSTALL_DIR "lib${LIB_SUFFIX}")
   ENDIF (EXISTS /etc/gentoo-release)
+  IF (EXISTS /etc/slackware-version)
+    SET (LIB_INSTALL_DIR "lib${LIB_SUFFIX}")
+  ENDIF (EXISTS /etc/slackware-version)
   IF(APPLE)
     IF (CMAKE_SIZEOF_VOID_P MATCHES "8")
 #      IF (CMAKE_OSX_64)
